PhD Position in Ultrafast Investigation of Anti-Kasha Photochemical Reactions in Molecular Systems

PhD student position “Ultrafast Investigation of Anti-Kasha Photochemical Reactions in Molecular Systems"
100 %

Institute of Applied Physics, University of Bern

The Kasha's rule is a fundamental principle of photophysics and photochemistry stating that photoinduced reactions in polyatomic molecules in the condensed phase occur with appreciable yield only in the lowest excited state of a given multiplicity, irrespective of the excitation wavelength. Its implications touch any aspect of photochemistry and photophysics and set severe limitations, for instance, to the efficiency of solar energy conversion by photovoltaic or photosynthetic systems, or to controlling, and not only triggering, a chemical reaction with light. It stands against the fabrication of multiresponsive materials, i.e. whose response could depend on the photon wavelength or on the number of excitations. Nevertheless, evidence of its violation has been reported for the major types of excited-state reactions, arousing a growing interest in anti-Kasha (aK) photophysics and -chemistry. A huge potential could be unleashed by increasing the number of chromophores for aK applications and, after a better comprehension of the fundamental mechanisms, learning how to design them. Indeed, a deep understanding of the fundamental mechanisms underneath aK photochemistry and designing more aK chromophores would open up an unexpectedly broad range of possibilities for selective control of photochemical reactions, and not only the reduction of energy losses in photonic devices. The aim of the project is to achieve such a keen understanding by means of state-of-the-art ultrafast electronic spectroscopies, complemented by molecular dynamics simulations.